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Prop question...max rpm
#1
We're headed to Powell the end of the month and I'm currently running a 19 pitch, 3 blade prop, on a 125 horse Mariner outboard 2 stroke, and I've found that when the boat is fully loaded with all our camping gear, people, etc. that I can't plain out. This time around we're going to good hope bay, and I think it would be ridiculous to go there if you can't plain out, it would take forever (about a 20 mile drive)! Currently the max rpm for my motor is 5250 and with the current prop it'll run ~5000 rpm max, so that's a good, it's virtually impossible to exceed the motor's designated maximum rpm. What I was thinking was to buy a 15 or 17 pitch prop to ensure I can plain out when fully loaded, and just be careful not to exceed 5250 rpm, what do you think? The prop doc says you don't ever even want the ability to exceed your max rpm, but at this point I don't know if I see an option. Let me know what your experience has been. I know they sell 11 pitch props, tell me that wouldn't exceed any boat's max rpm?
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#2
Have you experienced this problem at the 3652 elevation that Lake Powell is. My boat runs much better at the lower elevation of Powell. Just a thought.
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#3
I haven't noticed my rpms while I've been down there. All I know is my boat won't plain when it's fully loaded with gear while I'm down there. Plus I've felt I need a second prop on hand just in case I shred one while I'm down there.
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#4
How old is your motor, can you trim the motor? You should be able to get your boat on plane by triming it either up or dawn.
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#5
The motor is a 97'. Yes the motor trims, I always thought that max thrust is accomplished with the motor is straight up and down in relation to the hull of the boat? So I've always trimmed it down (near the stopping point), when towing skiers or when plaining out.
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#6
You can call overton's and talk to their tech department, give them your info on your boat and they can spec out props that are acceptable for your motor. I had a 19 pitch and by changing to a 17 pitch it dropped my trolling speed by 1/2 mph which is what I wanted....still plenty of power. its worth calling them.
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#7
also..how are you loading your boat? if all your weight is in the back of the boat it will be much harder to plane out
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#8
The prop questions is always a tough one, harder when at 4,000 ft elevation. I have a Ranger and just switched my prop. Was running a 23p and hole shot was a huge issue, I dropped to a 21p and hole shot is perfect (even with 4 people in boat, lost about 4 mph top end.
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#9
15 is to much . You would just not get enough bite . I would go with the 17 . If you don't have a plaining plate . Like a Whale Tail or Dolfin , get one . They bolt on your cavitation plate and make a big differance .
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#10
A 17 should help. As mentioned check how you are loading your boat. It may need to have the weight more evenly distributed. My boat likes the load towards the rear. Other boats I've owned wanted more weight up front to keep the bow down.
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#11
Yeah my boat seems to like to be loaded towards the front. We did shift stuff around, but it didn't help. I don't have a hydrofin, maybe something to look into.
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#12
My boat jumps up a lot faster with a hydra foil .
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#13
Look at the Stingray 300 . There are several different kind on ebay .
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#14
I'm with the prop doc with this one. Stick with the prop that keeps you in the recommended RPM of your motor at full throttle and get a hydro fin. Curt69 mentioned the stingrays 300 and I'd give that a +1. It made a big difference all the way around on my boat.

When I bought my boat it was propped wrong too. Awesome hole shot but I was over revving my motor big-time. It's kind of like driving your car down the freeway at 65 mph in second gear. Not a good idea.
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#15
How are you loading your boat when it is full? If all the weight is in the bow you will have a hard time planing out. But if you have all the weight in the stern you will never ever plane out. If you ass is too heavy your nose never will pull down.

As for trimming your motor, the bottom end if your tilt may be too deep. You never want your prop pointing lower then 90 degrees out, and actually a 5 - 10 degree tilt up is optimal. With your boat on the trailer trim your motor all the way down, see if the prop is pointing down or just straight. If it is down below 90 degrees you will dig too deep and again will never plane out.

Good luck on the trip.
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#16
In the past when I have a bunch of people in the boat, I'm not ever able to plain until people move towards the middle and maybe one or two people on the bow. So when we were at powell last year this is what we tried but it didn't work.

I'll have to look at the orientation of the motor in relation to the stern, but like I said in an earlier post, I don't ever launch with the motor trimmed down until it hits its limit, I always back it off a little bit, to about what you're saying, 5-10 degree tilt.
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#17
I have a brand new 17p in the box and am in the market for a 19p Tempest.
I would give you my prop and cash for your 19p if it is what I am looking for.
Is your motor a Merc 150 by any chance?
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#18
Are you exceeding your boats capacity . There should be a Coast Gaurd Sticker . Stateing the max number of people and total weight ?
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#19
From my calculations no. Though I heard that boat manufacturers will almost always put a smaller motor on a boat, keeps their cost down. So apparently it's a common issue to have too little of motor for the size of the boat. Not sure that's the case here.
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#20
The same sticker should have a max HP For your boat . If your boat will plane with the same load on your home waters , but won't at a lower elevetion . It could be a jetting problem in your carburetor . At lower elevations my boat runs alot better .
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